CN1527527A - Optical relay transmitting method and relay for wave division multiplexing - Google Patents

Abstract

A repeating apparatus disposed at an end point of each divisional repeating interval of a light transmission line performs a first dispersion compensation step (S1), an optical add/drop multiplexing step (S2) and a second dispersion compensation step (S3) to perform repeating transmission. The ratio of an over compensation amount at the second dispersion compensation step (S3) to the sum of dispersion compensation amounts at the first and second dispersion compensation steps (S1 and S2) is set so as to gradually vary together with the transmission distance from the terminal apparatus for transmission at which the repeating apparatus is disposed on the light transmission line so that degradation of wavelengths to be received by the terminal apparatus for reception is suppressed while dispersion compensation is performed with a high degree of accuracy at each optical add/drop multiplexing point on the transmission line.

Description

Wavelength division multiplexed light relay transmission method and relay

Technical field

The present invention relates to be suitable for the wavelength division multiplexed light relay transmission method and the relay of optical communication system.

Background technology

In recent years, because the use of communication network increases greatly, the demand that further improves network capacity is also increasing.In addition, in optical communication system, wish to improve capacity, speed and the distance of existing system, to satisfy the needs that network capacity improves.

Under existing situation, begun wavelength division multiplexing (WDM) optical transmission system of actual use based on every channel transmission rate of 10Gbit/s (gigabit/second).In the future,, need a kind of ultrahigh speed transmission system with 40Gbit/s or higher every channel transmission rate from the angle of the demand of capacity increase, frequency service efficiency and the cost in future.

Particularly in recent years, need make the optical network system multifunction.Like this, just not only need point-to-point transfer function, and need freely to change the function of photo-signal channel, for example Optical Add Drop Multiplexer (OADM) function and optical cross connect (OXC) function.

By the way, because the refractive index of optical fiber is according to wavelength change, so even use identical optical fiber, for different wavelength, the propagation time of light (speed) is also different.This phenomenon is called as chromatic dispersion.In the ultrahigh speed transmission system,, need carry out best compensation to the chromatic dispersion of transmission line, the waveform deterioration is carried out the compensation of high-precision the best for the multifunction of tackling above-mentioned network system and the raising of capacity.

Notice that following document discloses the technology relevant with the application's invention.

Patent documentation 1:

Japanese Patent Application Publication spy opens the 2000-68931 communique

Patent documentation 2:

U.S. Patent No. 6229935

By the way, in the optical transmission system with the required 40Gbit/s of above-mentioned ultrahigh speed transmission system or higher transmission rate, the tolerance of chromatic dispersion is very little.For example, under the situation of NRZ (non-return-to-zero (Non Return to Zero)) the method transmission wavelength-division-multiplexed optical signal that uses the 40Gbit/s transmission rate, dispersion tolerance is 1/16 of 10Gbit/s system less than about 70ps/nm (ps/nm).

Simultaneously, the transmission line CHROMATIC DISPERSION IN FIBER OPTICS relates to the difference in length such as transmission line, the changing factor of abbe number dispersion, transmission line optical fiber and the chromatic dispersion gradient coefficient of dispersion compensating fiber (DCF) and the variations in temperature of zero-dispersion wavelength of fiber etc. in the mill.In order to realize the transmission of long distance by the ultrahigh speed wave division multiplexing transmission system, make it possible to absorb this dispersion variation, and being suppressed at the deterioration of the reception waveform in the receiver side terminal installation, the branch on optical transmission line is inserted point to carry out high-precision dispersion compensation is important problem simultaneously.

Summary of the invention

The purpose of this invention is to provide a kind of wavelength division multiplexing optical transmission method and a kind of relay, can suppress the deterioration of the reception waveform in the receiver side terminal installation by them, the slotting point of the branch on optical transmission line carries out high-precision dispersion compensation simultaneously.

In order to achieve the above object, according to an aspect of the present invention, a kind of wavelength division multiplexed light relay transmission method is provided, be used for carrying out the relay transmission of wavelength multiplexing light signal along an optical transmission line, this optical transmission line is connecting transmission terminal installation and receiver terminal device, and have between the relay area of separating by a plurality of relays, this method comprises a plurality of steps by each execution in these a plurality of relays that are arranged on the end points place between these a plurality of separation relay area, these steps comprise: the first dispersion compensation step, be used for the chromatic dispersion that comprises in the wavelength multiplexing light signal of having propagated between the separation relay area that sends the terminal installation side is compensated, so that it is within the tolerance that sets in advance; The Optical Add Drop Multiplexer step is used for that each wavelength components of having carried out the wavelength multiplexing light signal that dispersion compensation handles in the first dispersion compensation step is carried out Optical Add Drop Multiplexer and handles; And the second dispersion compensation step, be used to use an overcompensation amount to carry out dispersion compensation and handle to having carried out wavelength multiplexing light signal that Optical Add Drop Multiplexer handles in the Optical Add Drop Multiplexer step, make the summation of the compensation rate of the second dispersion compensation step and the compensation rate of the first dispersion compensation step with between the separation relay area that sends the terminal installation side in the chromatic dispersion of appearance become predetermined ratio, and resulting signal is transferred between the separation relay area of receiver terminal device side, ratio to the chromatic dispersion compensation quantity summation of the overcompensation amount of the second dispersion compensation step and the first and second dispersion compensation steps is provided with, and makes it along with the residing position of relay on the optical transmission line gradually changes apart from the transmission range that sends terminal installation.

Preferably, be provided with being used for carrying out this predetermined ratio that dispersion compensation handles by this overcompensation amount, make it along with the position that is provided with relay on the optical transmission line increases gradually or reduces apart from the transmission range that sends terminal installation in the second dispersion compensation step.

This wavelength division multiplexed light relay transmission method can also comprise the residual chromatic dispersion compensation step by each execution in these a plurality of relays, when before handling and afterwards residual dispersion occurring in the light signal at each wavelength, this residual dispersion is compensated in the Optical Add Drop Multiplexer of Optical Add Drop Multiplexer step.

This wavelength division multiplexed light relay transmission method can also comprise the dispersion compensation step, is used for satisfying handling at the dispersion compensation of the transmission conditions that send the wavelength multiplexing light signal that terminal installation sends.In this case, preferably, these transmission conditions relate at least one in type, transmission range and the bit rate of optical fiber.

According to a further aspect in the invention, a kind of relay that is used for the wavelength division multiplexing light relay transmission system is provided, wherein, by an optical transmission line transmission terminal installation and receiver terminal device are interconnected, separate by a plurality of relays between the relay area of this optical transmission line, to carry out the relay transmission of wavelength multiplexing light signal, this relay comprises: the first dispersion compensation portion, be used for the chromatic dispersion that comprises in the wavelength multiplexing light signal of having propagated between the separation relay area that sends the terminal installation side is compensated, make it be in the tolerance that sets in advance; Optical Add Drop Multiplexer portion is used for that each wavelength components of having carried out the wavelength multiplexing light signal that dispersion compensation handles in the first dispersion compensation portion is carried out Optical Add Drop Multiplexer and handles; And the second dispersion compensation portion, be used to use an overcompensation amount to carry out dispersion compensation and handle to having carried out wavelength multiplexing light signal that Optical Add Drop Multiplexer handles by Optical Add Drop Multiplexer portion, make the summation of the compensation rate of the second dispersion compensation portion and the compensation rate of the first dispersion compensation portion with between the separation relay area that sends the terminal installation side in the chromatic dispersion of appearance become predetermined ratio.

Preferably, the second dispersion compensation portion carries out this predetermined ratio that dispersion compensation is handled along with the position that is provided with described relay on the optical transmission line increases gradually or reduces to be used for apart from the transmission range that sends terminal installation by this overcompensation amount.

In the first and second dispersion compensation portions at least one can be made of the variable dispersion compensation arrangement, and this variable dispersion compensation arrangement can change the set point of chromatic dispersion compensation quantity.

This relay can also comprise the dispersion slope compensation device, is used for compensating with the wavelength multiplexing light signal that will import Optical Add Drop Multiplexer portion or from the relevant chromatic dispersion gradient of the wavelength multiplexing light signal of one different Optical Add Drop Multiplexer portion output of these a plurality of relays.

This relay can also comprise dispersion compensator, and it compensates the residual dispersion amount about chromatic dispersion compensation quantity in the first or second dispersion compensation portion for each light signal by each channel of Optical Add Drop Multiplexer portion insertion/tap.

In wavelength division multiplexed light relay transmission method of the present invention and relay, the chromatic dispersion that comprises in the wavelength multiplexing light signal of propagating between the first dispersion compensation portion is to the separation relay area that is sending the terminal installation side compensates, after making it be in the tolerance interior (the first dispersion compensation step) that sets in advance, can carry out Optical Add Drop Multiplexer to each wavelength components of wavelength multiplexing light signal and handle (Optical Add Drop Multiplexer step).Therefore, can the chromatic dispersion of those light signals of being received by local station be optimized, to improve the characteristic of receiving optical signals.In addition, can the ratio of the chromatic dispersion compensation quantity summation of the overcompensation amount of the second dispersion compensation step and the first and second dispersion compensation steps be provided with, make it along with the position that is provided with relay on the optical transmission line gradually change apart from the transmission range that sends terminal installation (increase or reduce).Therefore, can carry out best compensation to the wavelength deterioration of the light signal of each wavelength of receiving by receiver terminal device.

In addition, when residual dispersion occurring in the light signal at each wavelength before or after handling, can in the residual chromatic dispersion compensation step, compensate this residual dispersion in the Optical Add Drop Multiplexer of Optical Add Drop Multiplexer step.Therefore, have and to prevent that the residual dispersion slope from accumulating the advantage of increase with the increase of transmission range.In addition, also have another advantage, promptly can be offset to regulate and import dispersion measure skew between the light signal of this relay from local station along with the dispersion measure between the wavelength optical signals that is transferred to local station from relay.

Above and other purpose of the present invention, feature and advantage will be from below in conjunction with the description of the drawings and accessory claims and become clear, and in the accompanying drawings, identical part or element are represented by identical label.

Description of drawings

Fig. 1 is the block diagram according to the wavelength division multiplexing light relay transmission system of first embodiment of the invention;

Fig. 2 is the block diagram according to the part of the relay of first embodiment of the invention;

Fig. 3 is the diagram according to the dispersion compensation pattern of the wavelength division multiplexing light relay transmission system of first embodiment of the invention;

Fig. 4 is the flow chart according to the operation of the relay of first embodiment of the invention;

Fig. 5 is the block diagram of a wavelength division multiplexing light relay transmission system, and the operation and the effect of first embodiment of the invention has been described;

Fig. 6 is the diagram of the dispersion compensation pattern of the wavelength division multiplexing light relay transmission system shown in Fig. 5;

Fig. 7 has shown the dispersion compensation effect of pattern shown in Figure 6;

Fig. 8 (a) has shown the dispersion compensation effect of pattern shown in Figure 6 to 8 (c);

Fig. 9 has shown the dispersion compensation effect of pattern shown in Figure 6;

Figure 10 is in first embodiment of the invention, and the quantity of relay is 5 o'clock, the block diagram of wavelength division multiplexing light relay transmission system;

Figure 11 is the diagram of the dispersion compensation pattern of the wavelength division multiplexing light relay transmission system shown in Figure 10;

Figure 12 is the block diagram according to the first improved wavelength division multiplexing light relay transmission system of first embodiment of the invention;

Figure 13 is the block diagram according to the second improved wavelength division multiplexing light relay transmission system of first embodiment of the invention;

Figure 14 is the diagram of the dispersion compensation pattern of the wavelength division multiplexing light relay transmission system shown in Figure 13;

Figure 15 is the diagram of another dispersion compensation pattern of the wavelength division multiplexing light relay transmission system shown in Figure 13;

Figure 16 is the block diagram according to the 3rd improved wavelength division multiplexing light relay transmission system of first embodiment of the invention;

Figure 17 is the block diagram according to the 4th improved wavelength division multiplexing light relay transmission system of first embodiment of the invention;

Figure 18 is the diagram of the dispersion compensation pattern of the wavelength division multiplexing light relay transmission system shown in Figure 17;

Figure 19 is the block diagram according to the wavelength division multiplexing light relay transmission system of second embodiment of the invention;

Figure 20 is the diagram of the dispersion compensation pattern of the wavelength division multiplexing light relay transmission system shown in Figure 19.

Embodiment

Below embodiment of the invention will be described with reference to drawings.

[A] first embodiment

Fig. 1 is the block diagram according to the wavelength division multiplexing light relay transmission system 1A of first embodiment of the invention.With reference to Fig. 1, shown in wavelength division multiplexing light relay transmission system 1A in, make by optical transmission line 40 to send terminal installation 10 and receiver terminal device 20 interconnects.Wavelength division multiplexing light relay transmission system 1A carries out for example relay transmission of the wavelength-division-multiplexed optical signal of each ripple 40Gbit/s.To 30-(N-1) optical transmission line 40 is divided between N relay area 40-1 to 40-N by N-1 relay 30-1.

In addition, wavelength division multiplexing light relay transmission system 1A can also be between above-mentioned relay area carries out the add drop multiplex of the light signal of each wavelength components in the transmission unit of 40-1 each in the 40-N to be handled, and the transmission wavelength-division-multiplexed optical signal.

Here, relay 30-1 has as being arranged on dead-beat relay that 40-1 between relay area locates to the end points (end points on transmitter side or the receiver side) of 40-N is carried out the add drop multiplex processing to wavelength-division-multiplexed optical signal function to 30-(N-1).Notice that relay 30-1 has the latent structure of hereinafter describing of the present invention to 30-(N-1).

40-1 is that light sends the interval that is connected by optical fiber 41-1 between terminal installation 10 and the relay 30-1 between relay area.Between relay area 40-2 to 40-(N-1) be adjacent relay 30-1 between the 30-(N-1) respectively by optical fiber 41-2 to interval that 41-(N-1) connects.40-N is the interval that is connected by optical fiber 41-N between relay 30-(N-1) and the light-receiving terminal installation 20 between relay area.

Send terminal installation 10 and comprise that a plurality of (being 44 in the example shown) light sending part 11-1 is to 11-44, multiplexer 12 and amplifier 13.These 44 light sending parts (Tx#1 is to Tx#44) 11-1 exports respectively to 11-44 has different wavelength X mutually ₁To λ ₄₄Light signal.In other words, can export 44 different light signals from these 44 signal optical source 11-1 to 11-44 with different mutually wavelength.

These 44 light signals that 12 pairs of multiplexers have different mutually wavelength carry out the wavelength division multiplexing processing, and export resulting signal.Amplifier 13 amplifies this wavelength-division-multiplexed optical signal and it is sent to optical transmission line 40 from multiplexer 12.Note,, in first embodiment, in sending terminal installation 10, do not carry out dispersion compensation and handle (compensation rate DCT=0) although can provide chromatic dispersion compensating function to amplifier 13.

Relay 30-1 respectively comprises as shown in Figure 2 amplifier 31, first dispersion compensator 32, optical demultiplexer 33, optical multiplexer 34, second dispersion compensator 35 and amplifier 36 to 30-(N-1).Notice that in Fig. 2, relay 30-1 is represented by public label 31 to 36 to a plurality of parts of 30-(N-1).In addition, also represent to 51-n to a plurality of parts of a plurality of local stations that 30-(N-1) links to each other with relay 30-1 by public label 51-1.

Amplifier 31 amplifies the wavelength-division-multiplexed optical signal by (wherein, relay point is relay 30-1,40-1 between relay area) between the relay area that sends terminal installation 10 sides.

First dispersion compensator 32 is for example formed by dispersion compensating fiber (DCF) etc., and to from the wavelength-division-multiplexed optical signal of amplifier 31 relevant chromatic dispersion carry out best compensation.In addition, first dispersion compensator 32 for example can be suitable for the dispersion compensating fiber (DCF) that relay 30-1 carries out dispersion compensation to the compensation rate of 30-(N-1) by as mentioned below can using and forms.

In addition, first dispersion compensator, 32 using compensation amount DCLa carry out dispersion compensation to be handled, and (is the λ of each wavelength setting with the middle wave band that will form wavelength-division-multiplexed optical signal ₁To λ ₄₄In λ ₂₂) wavelength in chromatic dispersion be suppressed within the dispersion tolerance or still less [for example 0].Therefore, carry out the wavelength division multiplex resolution process and output to the 50-1 of local station to have the dispersion measure of The optimal compensation by the optical demultiplexer of hereinafter describing 33, and its waveform deterioration has obtained compensation to the light signal of 50-n.

Therefore, above-mentioned first dispersion compensator 32 is used as the first dispersion compensation portion, is used for the chromatic dispersion that occurs in the optical transmission line between the relay area that sends terminal installation 10 sides is compensated, and makes it be in the tolerance that sets in advance.

33 pairs of optical demultiplexers carry out the wavelength division multiplex resolution process by the wavelength-division-multiplexed optical signal that first dispersion compensator 32 has carried out dispersion compensation, and the wavelength components of decomposing according to multichannel outputs to optical multiplexer 34 or the 50-1 of the local station acceptance division 51R to 50-n with resulting signal.Particularly, in a plurality of light signals that obtain by the wavelength division multiplex resolution process of being undertaken by optical demultiplexer 33, output to the acceptance division 51R (tap multiplexing process (droppingmultiplexing process)) of the 50-1 of local station with being assigned as the light signal of the 50-1 of each local station, and each light signal that will have any other wavelength that is different from just now the received signal wavelength of describing outputs to optical multiplexer 34 to 50-n to the received signal wavelength of 50-n.

34 pairs of light signals (wavelength is distributed to the light signal of the 50-1 of local station to 50-n respectively) from the light signal of optical demultiplexer 33 and the output of the sending part 51T from the 50-1 of local station to 50-n of optical multiplexer carry out wavelength division multiplexing to be handled, and exports resulting signal (inserting multiplexing process (addmultiplexing process)).Therefore, above-mentioned optical demultiplexer 33 and optical multiplexer 34 are used as Optical Add Drop Multiplexer portion, are used for carrying out Optical Add Drop Multiplexer and handling having carried out wavelength-division-multiplexed optical signal that dispersion compensation handles by first dispersion compensator 32 pairs of each wavelength components.

In addition, second dispersion compensator 35 is also formed by dispersion compensating fiber (DCF) etc.Second dispersion compensator 35 uses overcompensation amount DCLb to having carried out Optical Add Drop Multiplexer and handle and carried out dispersion compensation from the wavelength-division-multiplexed optical signal of optical multiplexer 34 outputs and handle, and makes 40-1 between summation and the relay area that sends terminal installation 10 sides of the compensation rate in wherein compensation rate and first dispersion compensator 32 become predetermined ratio to the chromatic dispersion of 40-(N-1) middle appearance.Thereby second dispersion compensator 35 is used as the second dispersion compensation portion.

36 pairs in amplifier has carried out the wavelength-division-multiplexed optical signals that dispersion compensation handles by second dispersion compensator 35 with this overcompensation amount and has amplified, and resulting signal is sent between the relay area of receiver terminal device 20 sides (being to be sent to 40-1 between relay area under the situation of relay 30-1 at relay point).

Therefore, for example, in relay 30-1, the Optical Add Drop Multiplexer of handling carry out first dispersion compensation that is undertaken by first dispersion compensator 32 from the wavelength-division-multiplexed optical signal of 40-1 between the relay area that sends terminal installation 10 sides, being undertaken by demultiplexer 33 and multiplexer 34 is handled and is handled by second dispersion compensation that second dispersion compensator 35 carries out.Then, resulting signal is sent to 40-2 between the relay area of next stage.

Equally in relay 30-2, to the wavelength-division-multiplexed optical signal that passes through 40-2 between relay area that sends from relay 30-1 carry out with described relay 30-1 just now those handle that similar first dispersion compensation is handled, Optical Add Drop Multiplexer is handled and second dispersion compensation is handled, and subsequently resulting signal is transferred to 40-3 between relay area in the next stage.

After this, also in relay 30-3 each in the 30-(N-1), carry out to above-mentioned relay 30-1 in those handle similar processing, and resulting wavelength-division-multiplexed optical signal is transferred between relay area in the next stage 40-4 to 40-N.

Now, be described in detail in chromatic dispersion compensation quantity DCLa and the DCLb that uses in first and second dispersion compensators 32 and 35 of each relay 30-1 in the 30-(N-1).Note, at relay 30-1 to 30-(N-1) in, the middle wavelength X of reference ₂₂In the dispersion measure amount of being compensated.In addition,, in 30-(N-1), also relate to and have its all band λ at each relay 30-1 ₁To λ ₂₁And λ ₂₃To λ ₄₄Light signal, be at these light signals under the state of wavelength-division-multiplexed optical signal, the compensation rate with gained as described below is carried out total dispersion compensation and is handled.In addition, in the described hereinafter receiver terminal device 20, each light signal with different wave length has been considered the dispersion compensation of chromatic dispersion gradient is handled.

At first, in the interval 40-1 of relaying, has middle wavelength X ₂₂Light signal in the dispersion measure that occurs be D ₁The time, for example the optimum dispersion compensation amount DCLa#1 in first dispersion compensator 32 among the above-mentioned relay 30-1 can be expressed as expression formula given below [1a].Therefore, in first dispersion compensator 32 in relay 30-1, can middle wavelength X will be had among the 40-1 between relay area ₂₂Light signal in the chromatic dispersion that occurs to suppress be 0 (with reference to the some C of Fig. 3 ₁).Here, this chromatic dispersion compensation quantity is the dispersion measure that is used for reducing the chromatic dispersion that wavelength-division-multiplexed optical signal occurs, and has negative value.

DCLa#1＝-D ₁…[1a]

In addition, as represented by expression formula given below [1b], the overcompensation amount DCLb#1 in second dispersion compensator 35 in can relay 30-1 is set to by will be by the middle wavelength X among the 40-1 between above-mentioned relay area ₂₂In the dispersion measure that occurs multiply by that a fixed value of calculating than β converts negative value to and the value (with reference to Fig. 3) that obtains.

DCLb#1＝-(β×D ₁)＝-βD ₁…[1b]

In addition, has middle wavelength X when hypothesis ₂₂Light signal in the dispersion measure that occurs when being derived between relay area 40-2, for example the optimum dispersion compensation amount DCLa#2 in first dispersion compensator 32 among the above-mentioned relay 30-2 can be expressed as expression formula given below [2a].

Particularly, with light signal from the moment that relay 30-1 is sent to 40-2 between relay area, have middle wavelength X ₂₂The dispersion measure of light signal equal value by expression formula [1b] expression.Therefore, added dispersion measure D ₂The dispersion measure (with reference to Fig. 3) of described just now value for compensating in will first dispersion compensator 32 in relay 30-2.Notice that actual compensation rate is to convert negative value to by the value with this dispersion measure to obtain.

DCLa#2＝-(-βD ₁+D ₂)＝βD ₁-D ₂…[2a]

In addition, as represented by expression formula given below [2b], the overcompensation amount DCLb#2 in second dispersion compensator 35 in can relay 30-2 is set to by will be by the summation D of the dispersion measure that occurs among 40-1 and the 40-2 between above-mentioned two relay area ₁+ D ₂Multiply by a fixed value of calculating than β and convert the value (with reference to Fig. 3) that negative value obtains to.

DCLb#2＝-{β×(D ₁+D ₂)}＝-β(D ₁+D ₂)…[2b]

Also can similarly calculate chromatic dispersion compensation quantity and overcompensation amount in relay 30-3 each first and second dispersion compensator 32 and 35 in the 30-(N-1) with those chromatic dispersion compensation quantities among above-mentioned relay 30-1 and the 30-2 and overcompensation amount.

Expression formula [3a] has represented to be used for relay 30-i[i; 2 to (N-1)] in first dispersion compensator 32 in the optimum dispersion compensation amount DCLa#i that compensates.In first dispersion compensator 32 of relay 30-2 in the 30-(N-1), the relay 40-2 in the previous stage can be had middle wavelength X in 40-(N-1) ₂₂Light signal in the chromatic dispersion that occurs to suppress be 0 (with reference to the some C of Fig. 3 ₂To C _N-1).

In addition, expression formula [3b] has represented to be used for relay 30-i[i; 2 to (N-1)] in second dispersion compensator 35 in the overcompensation amount DCLb#i (with reference to Fig. 3) that compensates.Particularly, can overcompensation amount DCLb#i being set to summation by the dispersion measure that will be occurred in the 40-(i-1) by 40-1 between relay area multiply by a fixed value of calculating than β and converts the value (with reference to Fig. 3) that negative value obtains to.

$\mathrm{DCLa}\#i=\mathrm{\β}\underset{j=1}{\overset{i=1}{\mathrm{\Σ}}}{D}_j-D_i\·\·\·\·\left[3a\right]$

$\mathrm{DCLb}\#i=-\mathrm{\β}\underset{j=1}{\overset{i}{\mathrm{\Σ}}}{D}_j\·\·\·\·\left[3b\right]$

Particularly, utilize in middle wavelength X by the wavelength-division-multiplexed optical signal of 40-(i-1) propagation between relay area ₂₂The middle chromatic dispersion D that occurs _iAnd the accumulated value of the compensation rate of 40-1 in the 40-(i-1) between relay area, can obtain the optimum dispersion compensation amount DCLa#i in first dispersion compensator 32.In addition, [3b] is given as above expression formula, and when increasing apart from the transmission range that sends terminal installation 10, this overcompensation amount increases (absolute value in the expression formula [3b] increases).

In addition, by the chromatic dispersion compensation quantity in second dispersion compensator 35 among the above-mentioned relay 30-1 of expression formula given below [4-1] calculating and the ratio R of the chromatic dispersion compensation quantity summation in first and second dispersion compensators 32 and 35 ₁In addition, can be by expression formula given below [4-i], use the result of expression formula [3a] and [3b] to calculate the ratio R of the chromatic dispersion compensation quantity summation in the chromatic dispersion compensation quantity in second dispersion compensator 35 and first and second dispersion compensators 32 and 35 among the relay 30-i _iNotice that the situation that this expression formula [4-i] also can be applied to i=1 (is R ₁).

${\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="A20041000318800331.png,A20041000318800341.png"\; state="\{\{state\}\}">R</figure-callout>}}_1=\frac{-\mathrm{\&beta;}{D}_1}{-\mathrm{\&beta;}{D}_1-{\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="A20041000318800331.png,A20041000318800341.png"\; state="\{\{state\}\}">D</figure-callout>}}_1}=\frac{\mathrm{\&beta;}}{\mathrm{\&beta;}+1}\&CenterDot;\&CenterDot;\&CenterDot;[4-1]$

$R_i=\frac{-\mathrm{\&beta;}\underset{j=1}{\overset{i}{\mathrm{\&Sigma;}}}{D}_j}{\mathrm{\&beta;}\underset{j=1}{\overset{i-1}{\mathrm{\&Sigma;}}}{D}_j-D_i-\mathrm{\&beta;}\underset{j=i}{\overset{i}{\mathrm{\&Sigma;}}}{D}_i}=\frac{\mathrm{\&beta;}}{1+\mathrm{\&beta;}}\underset{j=1}{\overset{i}{\mathrm{\&Sigma;}}}\frac{D_j}{D_i}\&CenterDot;\&CenterDot;\&CenterDot;[4-i]$

Here, the last item that is not included in the sum term of the expression formula that obtains in the expression formula [4-i] has often value, then value (with the increase of i value) (D who has along with transmission range increases gradually _i＞0).Particularly, to the ratio R of the chromatic dispersion compensation quantity summation of the overcompensation amount in the second dispersion compensation portion 35 and first and second dispersion compensators 32 and 35 _iBe provided with, make its along with relay 30-i to the transmission range that sends terminal installation 10 and gradually change (increasing gradually).

Note, increase gradually and represented a kind of phenomenon, that is, and the ratio R of overcompensation amount _iAlong with the transmission range to transmission terminal installation 10 increases gradually, and can not reduce midway.In addition, as mentioned below, because the ratio R that the ratio of the chromatic dispersion compensation quantity summation of the overcompensation amount in second dispersion compensator 35 and first and second dispersion compensators 32 and 35 is set to increase gradually _iSo, can be than at this ratio being the waveform deterioration that suppresses better under other situations of constant in the receiver terminal device 20.

The structure of receiver terminal device 20 will be described by the way, below.Receiver terminal device 20 comprise dispersion compensator/ amplifier 20,22,44 Variable Dispersion Compensators of demultiplexer (VDC) 23-1 to 23-44 and 44 light receiver 24-1 to 24-44.

21 pairs in dispersion compensator/amplifier amplifies by the wavelength-division-multiplexed optical signals of 40-N input between relay area, and the chromatic dispersion D of accumulated value to occurring in the wavelength-division-multiplexed optical signal of propagating by 40-N between relay area of the overcompensation amount of 40-1 in the 40-N between using compensation amount DCR and relay area _NCompensate.Note described just now chromatic dispersion D _NValue also be wave band λ in the middle of appearing at ₂₂In dispersion values.

Particularly, wavelength-division-multiplexed optical signal is being sent to the moment of 40-N between relay area, middle wave band λ from relay 30-(N-1) ₂₂Dispersion measure be DCLb# (N-1) (with reference to expression formula [3b]).Therefore, can use above-mentioned dispersion values D _N, provide and to be reduced to zero middle wavelength X by dispersion compensator/amplifier 21 by expression formula [5] ₂₂The compensation rate DCR (with reference to Fig. 3) of chromatic dispersion of light signal.

$\mathrm{DCR}=-(-\mathrm{\&beta;}\underset{j=1}{\overset{n-1}{\mathrm{\&Sigma;}}}{D}_j+D_N)=-D_N+\mathrm{\&beta;}\underset{j=1}{\overset{n-1}{\mathrm{\&Sigma;}}}{D}_j\&CenterDot;\&CenterDot;\&CenterDot;\left[5\right]$

Demultiplexer 22 will carry out the wavelength multichannel from the Wave division multiplexing light signal of dispersion compensator/amplifier 21 and decompose, and be decomposed into 44 different wavelength components.Variable Dispersion Compensator 23-1 compensates the residual dispersion in the light signal that is carried out the decomposition of wavelength multichannel by demultiplexer 22 respectively to 23-44.Therefore, can eliminate the influence of the chromatic dispersion gradient that dispersion measure is different between different wave length, and the dispersion values of the light signal of these wavelength is reduced to optimum value zero.

Light receiver 24-1 to 24-44 respectively to 23-44 the light signal that the dispersion values of each wavelength has carried out The optimal compensation being received processing by Variable Dispersion Compensator 23-1.

Because the wavelength division multiplexing light relay transmission system 1A in the first embodiment of the invention has above-mentioned structure, so can compensate to wavelength-division-multiplexed optical signal, and for the light signal of relay 30-1 to 30-(N-1) tap, use as hereinafter described in the optimal compensation amount their chromatic dispersion is compensated.

At first, when send 10 pairs of terminal installations wherein wavelength division multiplexing 44 different wave length λ ₁To λ ₄₄Wavelength-division-multiplexed optical signal carry out signal when sending, can not occur in optical fiber, propagating and the chromatic dispersion that causes in this moment by light signal.

In addition, shown in the flow chart of Fig. 4, at each relay 30-1 that is arranged in the end points place between each relay area to 30-(N-1), the chromatic dispersion that comprises in the wavelength-division-multiplexed optical signal to the propagation in the 40-(N-1) of 40-1 between the relay area that sends terminal installation 10 sides compensates, make it be in (the first dispersion compensation step, step S1) in the tolerance that sets in advance by first dispersion compensator 32.Particularly, the chromatic dispersion of wavelength-division-multiplexed optical signal is compensated (using compensation amount DCLa), make as indicated above in the middle of wavelength X ₂₂Chromatic dispersion can be reduced to zero.

Then, the wavelength-division-multiplexed optical signal that has carried out dispersion compensation by demultiplexer 33 and 34 pairs of multiplexers in the first dispersion compensation step carries out Optical Add Drop Multiplexer and handles (Optical Add Drop Multiplexer step, step S2).Particularly, carry out the light signal that Optical Add Drop Multiplexer handles and be in the state that its chromatic dispersion has obtained The optimal compensation.Therefore, the 50-1 of local station can receive the light signal that the waveform deterioration obtains The optimal compensation to 50-n.

In addition, second dispersion compensator 35 carries out the dispersion compensation processing with overcompensation amount DCLb to carried out the wavelength-division-multiplexed optical signal that Optical Add Drop Multiplexer is handled and thereby its chromatic dispersion overcompensation is within the above-mentioned tolerance in the Optical Add Drop Multiplexer step, the summation of the chromatic dispersion that occurs between the summation that makes the compensation rate in compensation rate and second dispersion compensator 35 in the dispersion compensator 32 of winning and relay area becomes predetermined ratio, and resulting signal is sent between the relay area of receiver terminal device side (the second dispersion compensation step, step S3).

At this moment, to carry out first wavelength-division-multiplexed optical signal that dispersion compensation handles with above-mentioned overcompensation amount by second dispersion compensator 35 at the previous relay (30-1) in two adjacent on the transmission line 40 relays (for example, relay 30-1 and 30-2) and be sent to 30-2 (the second dispersion compensation step) between the relay area of receiver terminal device 20 sides.The relay 30-2 in back compensates the chromatic dispersion that comprises in first wavelength-division-multiplexed optical signal, makes it be in the tolerance that sets in advance (the first dispersion compensation step).

In addition, at relay 30-i[i; 1 to (N-1)] in, carrying out dispersion compensation ratio R to the compensation rate in the overcompensation amount in first dispersion compensator 32 and second dispersion compensator 35 when handling _iBe provided with, make it along with the transmission range from the transmission terminal installation 10 on the optical transmission line 40 to relay 30-i increases gradually.Therefore, can carry out best compensation to the waveform deterioration of the light signal of each wavelength of receiving by receiver terminal device 20.

In addition, occur under the situation of residual dispersion in the wavelength-division-multiplexed optical signal that is received by receiver terminal device 20, Variable Dispersion Compensator 23-1 compensates the residual dispersion of each light signal of each wavelength to 23-44.

Fig. 5 to 7,8 (a) shown in the described wavelength division multiplexing light relay transmission system of reference Fig. 1 1A to 8 (c) and 9, and processing that can be by utilizing the overcompensation amount in the 30-(N-1) at relay 30-1 is carried out best compensation to the waveform deterioration of the wavelength-division-multiplexed optical signal that received by receiver terminal device 20.

Here, in wavelength division multiplexing light relay transmission system 3 shown in Figure 5, send terminal installation 10 and interconnect by optical transmission line 70, to carry out the linear relay transmission of wavelength-division-multiplexed optical signal with receiver terminal device 20.In optical transmission line 70, its relaying interval (spacing) 70-1 is limited to 60-5 by 5 linear relay 60-1 respectively to 70-6.In addition, 70-1 is formed to 71-6 by the optical fiber 71-1 that length is approximately 100km respectively to 70-6 between relay area.

Particularly, different with the wavelength division multiplexing light relay transmission system 1A among first embodiment shown in Figure 1, wavelength division multiplexing light relay transmission system 3 does not comprise relay 30-1 to 30-(N-1), and comprises that the linear relay 60-1 with Optical Add Drop Multiplexer function is to 60-5.Note, in Fig. 5, represent by identical label with essentially identical element among Fig. 1.

In addition, linear relay 60-1 respectively comprises amplifier 61 and dispersion compensator 62 to 60-5.Similar in the 30-(N-1) to relay 30-1, dispersion compensator 62 uses an overcompensation amount that the dispersion measure on the transmission line between corresponding relay area is compensated, and sends resulting signal to 70-2 between the relay area next one in the 70-6.

In this case, wherein, at linear relay 60-1 in 60-5, to the middle wave band λ of 70-1 between the relay area of front in the 70-5 ₂₂Transmission line dispersion measure D accumulative total carried out 114% compensation deals (14% of dispersion measure D overcompensation amount [chromatic dispersion amount of bias (dispersion shear amount)] Δ D in by way of compensation wherein _L, with reference to Fig. 6), the overcompensation amount that linear relay 60-1 is accumulated in the 60-5 is respectively Δ D _L, 2 Δ D _L, 3 Δ D _L, 4 Δ D _L, and 5 Δ D _LParticularly, similar to above-mentioned first embodiment, the overcompensation amount that relay 60-1 is accumulated in the 60-5 is provided with, and makes it along with increasing gradually to the transmission range that sends terminal installation 10.

As mentioned above, 70-1 is formed by the monomode fiber (SMF) of the length with about 100km to 70-5 between relay area, therefore, 70-1 between relay area can be controlled to be the basic mutually dispersion measure D that equates to the transmission line dispersion measure among the 70-5.In this case, the expression formula [4-i] that above provides can be expressed as expression formula given below [4 '].Note, under the situation of carrying out overcompensation processing (β＞0) by second dispersion compensator 35, can think that this value is along with increasing gradually to the transmission range that sends terminal installation 10.

$R_i=\frac{\mathrm{\&beta;}}{D_i(1+\mathrm{\&beta;})}\underset{j=1}{\overset{i}{\mathrm{\&Sigma;}}}{D}_j=\frac{\mathrm{\&beta;}}{(1+\mathrm{\&beta;})}\&times;i\&CenterDot;\&CenterDot;\&CenterDot;\left[4^{,}\right]$

In having the wavelength division multiplexing light relay transmission system 3 of above-mentioned this structure, when the wavelength deterioration of the wavelength-division-multiplexed optical signal that will be received by receiver terminal device 20 compares between following two kinds of situations, can obtain result described below, wherein a kind of situation be at linear relay 60-1 in 60-5, for example use dispersion compensation coefficient 114% (14% of dispersion measure D overcompensation amount [chromatic dispersion amount of bias] Δ D in by way of compensation wherein _L, with reference to Fig. 6) and to wave band λ in the middle of each spacing above-mentioned ₂₂In transmission line dispersion measure D compensate processing, another kind of situation is that the dispersion compensation that carries out is as shown in Figure 7 handled.

Here, in Fig. 7, the linear relay 60-1 in structure and similar wavelength division multiplexing light relay transmission system 1A ' shown in Figure 5 to 60-5 to the middle wave band λ of the interval 70-1 of relaying in the 70-5 ₂₂The middle transmission line dispersion measure A that occurs ₁To A ₆Carry out the dispersion compensation coefficient and be 100% dispersion compensation and handle, handle, and will send receiver terminal device 20 to by the wavelength-division-multiplexed optical signal that the dispersion measure that label B1 represents to B5 is passed through The optimal compensation and do not carry out overcompensation.

At this moment, under situation as Fig. 6 or next definite setting that linear relay 60-1 is handled to the dispersion compensation among the 60-5 shown in Figure 7, when the waveform deterioration of the wavelength-division-multiplexed optical signal that will be received by receiver terminal device 20 compares mutually, can obtain as Fig. 8 (a) to the comparative result as shown in 8 (c).

Fig. 8 (a) has shown that to 8 (c) Q relevant with residual dispersion (the total dispersion amount of transmission line and dispersion compensator) worsens the comparative result of (Qpenalty) (the deterioration amount of the Q value of expression waveform characteristic) under the situation of the dispersion compensation processing of carrying out shown in Fig. 6 and 7.

Here, the Q deterioration is the difference between the end-to-end value (back-to-back value) of Q value and the value of passing through the later Q value of transmission line.The Q value is by photosignal waveform being changed into the signal of telecommunication obtaining eye pattern (eye pattern) and to obtain along the longitudinal direction at the center of this eyelet under the situation of cross section of this eyelet, the value that the summation of the standard deviation of the sample distribution of the standard deviation of the sample distribution of " 1 " side and " 0 " side is obtained to the distance between the center of " 0 " side sample distribution divided by the center of " 1 " side sample distribution.

Here, Fig. 8 (a) has shown the example that all residual dispersion values is marked the Q deterioration.In addition, the distribution of the residual dispersion value the when point of being represented by black triangle represents that carrying out 114% dispersion compensation shown in Figure 6 handles, and the distribution of the residual dispersion value when representing that by the point that black squares is represented carrying out 100% dispersion compensation shown in Figure 7 handles.In addition, Fig. 8 (b) has shown the eye pattern when carrying out 114% dispersion compensation shown in Figure 6 handles, and Fig. 8 (c) has shown the eye pattern when carrying out 100% dispersion compensation shown in Figure 7 handles.

Shown in Fig. 8 (a), when carrying out 114% overcompensation processing shown in Figure 6, can reduce the value that Q worsens, and can be than carrying out the better off ground inhibition waveform deterioration that 100% dispersion compensation shown in Figure 7 is handled.

Note, when when described waveform deterioration was estimated just now, must regulate to the chromatic dispersion compensation quantity summation (DCR+VDC) among the 23-44 dispersion compensator/amplifier 21 in the above-mentioned receiver terminal device 20 and Variable Dispersion Compensator 23-1, residual dispersion strictly is set to zero.

Fig. 9 has shown in wavelength division multiplexing light relay transmission system 3 shown in Figure 5, chromatic dispersion compensation quantity DCR in dispersion compensator/amplifier in the receiver terminal device 20 21 is being regulated residual dispersion being reduced under zero the situation, linear relay 60-1 Q in the 60-5 worsens dispersion measure * (the 1-dispersion compensation coefficient) with respect to dispersion-shifted each section of amount Δ D[] characteristic.

As shown in Figure 9, undertaken under the situation of 114% overcompensation processing by dispersion compensator 62 in 60-5 at linear relay 60-1, the value that Q worsens is lower than the situation of carrying out 100% compensation deals.Particularly, when dispersion-shifted amount Δ D is corresponding with about 105% to 120% dispersion compensation coefficient, the value that Q worsens is suitable, particularly, the value of side-play amount for or when being roughly with the corresponding Δ D=-200ps/nm of about 114% dispersion compensation coefficient, it is only that Q worsens.

In wavelength division multiplexing light relay transmission system 1A ' shown in Figure 10, to 30-5 transmission line 40 is divided between 6 relay area 40-1 to 40-6 by 5 relay 30-1 among the wavelength division multiplexing light relay transmission system 1A that above describes with reference to Fig. 1.In addition, 40-1 is formed by the monomode fiber of the length with about 100km to 40-6 between relay area, and can be with the middle wave band λ in them ₂₂The middle dispersion measure that occurs suppresses for equaling dispersion measure D substantially.

In addition, relay 30-1 uses 100% dispersion compensation coefficient to compensate processing to first dispersion compensator 32 of 30-5, and second dispersion compensator 35 uses the overcompensation coefficient of β=10% to carry out the overcompensation processing.In other words,, can carry out the dispersion compensation processing by 110% dispersion compensation coefficient, wherein can obtain only Q and worsen by the cooperation of first dispersion compensator 32 and second dispersion compensator 35.

In this case, first dispersion compensator, 32 using compensation amount-D of relay 30-1 carry out dispersion compensation to be handled, and second dispersion compensator 35 of relay 30-1 uses overcompensation amount-0.1D to carry out the overcompensation processing.Similarly, first dispersion compensator, 32 using compensation amount-D of relay 30-2 carry out dispersion compensation to be handled, and second dispersion compensator 35 of relay 30-2 uses overcompensation amount-0.1D to carry out the overcompensation processing.

Similarly, also can use the expression formula [3a] that above provides and [3b] calculate relay 30-2 in the 30-5 first and second dispersion compensators 32 and 35 compensation rate and overcompensation amount.

Particularly, compensation rate DCLa#1 in first dispersion compensator 32 of relay 30-2 in the 30-5 to DCLa#5 represent respectively-0.9D ,-0.8D ,-0.7D ,-0.7D and-0.6D, and the compensation rate in second dispersion compensator 35 of relay 30-2 in the 30-5 represent respectively-0.1D ,-0.2D ,-0.3D ,-0.4D and-0.5D (with reference to Figure 11).

In this way, according to the first embodiment of the present invention, the compensation of the best is carried out in the chromatic dispersion that comprises in the wavelength-division-multiplexed optical signal that 30-1 propagates to 30-(N-1) between 32 pairs of first dispersion compensators are by the relay area that sends terminal installation 10 sides, after making it be in the tolerance interior (the first dispersion compensation step) that sets in advance, can carry out Optical Add Drop Multiplexer by optical demultiplexer 33 and optical multiplexer 34 and handle (with reference to Fig. 2) (Optical Add Drop Multiplexer step).Therefore, can be to carrying out best compensation to the chromatic dispersion of the light signal of 50-n reception, to improve the characteristic of receiving optical signals by the 50-1 of local station.In addition, can be provided with being used for using the overcompensation amount to carry out the predetermined ratio R that dispersion compensation handles, make it along with the transmission range of (N-1) increases gradually to relay 30-1 to 30-from the transmission terminal installation 10 on the optical transmission line 40 in the second dispersion compensation step.Therefore, can carry out best compensation to the waveform deterioration of the light signal of each wavelength of receiving by receiver terminal device 20.

First of [B] first embodiment improves

Figure 12 is the block diagram according to the first improved wavelength division multiplexing light relay transmission system 1B of first embodiment of the invention.With reference to Figure 12, shown wavelength division multiplexing light relay transmission system 1B is with above different with reference to the described wavelength division multiplexing light relay transmission system of Fig. 1 1A, and its difference is that relay 30-1 is formed by the Variable Dispersion Compensator (VDC) of the setting that can change dispersion measure to the first and second dispersion compensator 32B of 30-5 and 35B.Except described difference just now, the structure of the structure of wavelength division multiplexing light relay transmission system 1B and wavelength division multiplexing light relay transmission system 1A is basic identical.

In addition, as the relay 30-1 of formation as described in just now in 30-5, with similar among first embodiment, at the first dispersion compensator 32B chromatic dispersion that 40-1 between by the relay area that sends terminal installation 10 sides comprises in the wavelength-division multiplex signals of 40-(N-1) propagation is compensated, after making it be in the tolerance interior (the first dispersion compensation step) that sets in advance, can handle the predetermined ratio R of (in the second dispersion compensation step) and be provided with being used for using the overcompensation amounts to carry out dispersion compensation, make it along with the transmission range of (N-1) increases gradually to relay 30-1 to 30-from the transmission terminal installation 10 on the optical transmission line 40 at dispersion compensator 35.Therefore, can realize and the similar advantage of described first embodiment above by wavelength division multiplexing light relay transmission system 1B.

In addition, relay 30-1 shown in Fig. 1 (or Fig. 5) is in the structure of 30-5 in above-mentioned first embodiment, must be equipped with first and second dispersion compensators 32 and the 35 corresponding different fixedly dispersion compensators in a large number in the 30-(N-1) with relay 30-1.Yet, according to this improved structure, only need to be equipped with one type Variable Dispersion Compensator, and change set point wherein.Therefore, can easily be configured to the network of dispersion compensation.In addition, also has an advantage, even wherein change transmission parameters such as bit rate and transmission line length, with the ratio that changes the chromatic dispersion compensation quantity of front and back at different levels or the optimal value of total amount, if changed the setting of the compensation rate of this Variable Dispersion Compensator, also can easily solve the problem of described variation just now.

Second of [C] first embodiment improves

Figure 13 is the block diagram according to the second improved wavelength division multiplexing light relay transmission system 1C of first embodiment of the invention.With reference to Figure 13, shown wavelength division multiplexed light relay transmission device 1C is with above different with reference to the described wavelength division multiplexing light relay transmission system of Fig. 1 1A, its difference is, except that the parts shown in Fig. 2, relay 30-1 also comprises in the one-level before the add drop multiplex of optical multiplexer 33 is handled to 30-5 and is used for variable dispersion slope equalizer 37 that the variable dispersion slope is compensated.

In structure shown in Figure 5, the ratio of the chromatic dispersion compensation quantity in first and second dispersion compensators 32 and 35 is regulated, make at centre wavelength (for example, λ ₂₂) in relay 30-1 is reduced to zero to the residual dispersion among the 30-5.Yet, in fact, because the residual dispersion slope in transmission line optical fiber and the dispersion compensator, one other channel is being carried out position that Optical Add Drop Multiplexer handles (with reference to the some C of Figure 14 ₁To C ₅) dispersion measure located can remain on one dispersion tolerance is had on the effect.

For example, the dispersion measure that occurs in the wavelength-division-multiplexed optical signal of propagating by optical fiber 41-1 comprises wavelength components λ as shown in figure 14 ₁In dispersion measure D λ ₁, wavelength components λ ₂₂In another dispersion measure D λ ₂₂, and wavelength components λ ₄₄In another dispersion measure D λ ₄₄Situation under, if only by first and second dispersion compensators 32 and 35 pairs of central wavelength lambda ₂₂Carry out dispersion compensation and handle, then work as transmission range, when promptly relaying progression increased, residual dispersion can be accumulated increase.

For example, when with relay 30-1 in carry out another location that add drop multiplex handles (with reference to the C of Figure 14 ₁) residual dispersion amount DC1 λ ₁To DC1 λ ₄₄Chromatic dispersion when comparing, in relay 30-5, carry out position that add drop multiplex handles (with reference to the C of Figure 14 ₅) the residual dispersion amount DC5 λ of each wavelength ₁To DC5 λ ₄₄Chromatic dispersion show as accumulation and increase.

Relay 30-1 in this improvement is provided the variable dispersion slope equalizer 37 in the 30-5, aforesaid this chromatic dispersion gradient is compensated in each relaying level, and the chromatic dispersion gradient that carries out the wavelength-division-multiplexed optical signal after dispersion compensation is handled by first dispersion compensator 32 compensated, make wavelength X ₁To λ ₄₄Dispersion measure and wavelength X ₂₂Dispersion measure (dispersion measure is zero point, with reference to the some C of Figure 15 ₁To C ₅) equate.Therefore, can when increasing, transmission range prevent that the accumulation of residual dispersion slope from increasing.

At relay 30-1 with above-mentioned structure in 30-5, Optical Add Drop Multiplexer (being undertaken by optical demultiplexer shown in Figure 2 33 and optical multiplexer 34) in the Optical Add Drop Multiplexer of Optical Add Drop Multiplexer step is handled compensates (residual chromatic dispersion compensation step) by 37 pairs of these residual dispersions of variable dispersion slope equalizer before and when residual dispersion occurring in the light signal of each wavelength afterwards.

More specifically, by 37 pairs of variable dispersion slope equalizers by relay 30-1 to first dispersion compensator 32 of 30-5 use a dispersion measure (this dispersion measure make in the middle of wavelength X ₂₂Dispersion measure be reduced to zero) (the first dispersion compensation step) residual dispersion slope of having carried out the wavelength-division-multiplexed optical signal of compensation compensates (residual chromatic dispersion compensation step).

For the wavelength-division-multiplexed optical signal that in this way the residual dispersion slope has been carried out compensation, undertaken by optical demultiplexer 33 and optical multiplexer 34 Optical Add Drop Multiplexer handle, undertaken by second dispersion compensator 35 second dispersion compensation is handled and carry out processing and amplifying by amplifier 36 after, send it between the relay area in the next stage 40-2 to 40-6.

In this way, improve according to second of first embodiment of the invention, (this dispersion measure makes middle wavelength X can to use a dispersion measure in the first dispersion compensation step by 37 pairs of variable dispersion slope equalizers in the residual chromatic dispersion compensation step ₂₂Dispersion measure be reduced to zero) the residual dispersion slope that carried out the wavelength-division-multiplexed optical signal of compensation compensates.Therefore, can when increasing, transmission range prevent that the accumulation of residual dispersion slope from increasing.

In addition, owing to can be provided with at the predetermined ratio R that second dispersion compensator 35 uses the overcompensation amount to carry out dispersion compensation processing (in the second dispersion compensation step) to being used for, make it along with the transmission range of (N-1) increases gradually to relay 30-1 to 30-from the transmission terminal installation 10 on the optical transmission line 40, so can realize advantage with the wavelength division multiplexed light relay transmission system similarity of above-mentioned first embodiment by wavelength division multiplexing light relay transmission system 1C.

Note, though in Figure 13, variable dispersion slope equalizer 37 is used for the compensation of residual dispersion slope, but according to the present invention, the method of compensation is not limited thereto, can also be equipped with the different fixedly dispersion slope compensation device of a plurality of Different Slope values, thereby use the fixedly dispersion slope compensation device that is suitable for the chromatic dispersion gradient residual volume of middle actual measurement between this relay area to 40-5 for 40-1 between each relay area.

In addition, where necessary, the position that can aforesaid this dispersion slope compensation device be arranged on first dispersion compensator, 32 back (for example, the position A of relay 30-1 among Figure 13), be arranged on another position (C) of second dispersion compensator, 35 fronts or another position (D) of second dispersion compensator, 35 back.In addition, the dispersion compensator that above-mentioned position (A is to D) can be located is arranged as suitable combination.

The 3rd of [D] first embodiment improves

Figure 16 is the block diagram according to the 3rd improved wavelength division multiplexing light relay transmission system 1D of first embodiment of the invention.With reference to Figure 16, shown wavelength division multiplexing light relay transmission system 1D is with above different with reference to the described wavelength division multiplexing light relay transmission system of Fig. 1 1A, its difference is, except the parts shown in Fig. 2, relay 30-1 to 30-5 also comprise Variable Dispersion Compensator 38-1 to 38-n and 39-1 to 39-n.

With reference in the described structure of Fig. 5, the ratio between the chromatic dispersion compensation quantity of first dispersion compensator 32 and second dispersion compensator 35 is regulated hereinbefore, make each relay 30-1 in the 30-5 at middle wave band λ ₂₂The middle residual dispersion that occurs can be reduced to zero.Except the dispersion compensation that is undertaken by above described first dispersion compensator 32 and second dispersion compensator 35 was handled, the Variable Dispersion Compensator 38-1 in this improvement compensated to the residual dispersion slope of the light signal of 50-n being transferred to the 50-1 of local station respectively to 38-n.Simultaneously, Variable Dispersion Compensator 39-1 compensates the residual dispersion slope that will join the light signal the wavelength-division-multiplexed optical signal on the optical transmission line 40 from the 50-1 of local station to 50-n respectively to 39-n.

At each relay 30-1 of the wavelength division multiplexing light relay transmission system 1D with above-mentioned structure in 30-5, if before the Optical Add Drop Multiplexer in the Optical Add Drop Multiplexer processing (being undertaken) of Optical Add Drop Multiplexer step and afterwards (in this example by optical demultiplexer shown in Fig. 2 33 and optical multiplexer 34, after optical tapoff is multiplexing and before the light insertion is multiplexing) residual dispersion appears in the light signal of a wavelength, and then 37 pairs of these residual dispersions of variable dispersion slope equalizer compensate (residual chromatic dispersion compensation step).

Particularly, by 33 pairs of optical demultiplexers by each relay 30-1 to first dispersion compensator 32 of 30-5 use a dispersion measure (this dispersion measure make in the middle of wavelength X ₂₂Dispersion measure be reduced to zero) (the first dispersion compensation step) wavelength-division-multiplexed optical signal of having carried out compensation carries out the wavelength multichannel and decomposes, and respectively with resulting have be appointed as the 50-1 of local station and export to Variable Dispersion Compensator 38-1 to 38-n to the light signal of the wavelength of the reception wavelength of 50-n.Variable Dispersion Compensator 38-1 compensates to the residual dispersion slope of the light signal of 50-n being transferred to the 50-1 of local station respectively to 38-n, and subsequently with the optical signal transmission of relevant wavelength to the 50-1 of local station to 50-n.

On the other hand, will be input to Variable Dispersion Compensator 39-1 respectively to 39-n to the light signal of 50-n, to 39-n its residual dispersion slope be compensated by Variable Dispersion Compensator 39-1 from the 50-1 of local station.Then, carrying out Optical Add Drop Multiplexer from Variable Dispersion Compensator 39-1 to the light signal of 39-n by 34 pairs of optical multiplexers handles.

In this way, improve according to the 3rd of first embodiment of the invention, can be by Variable Dispersion Compensator 38-1 to 38-n and 39-1 to 39-n to compensating with residual dispersion slope by the light signal (will be sent to the 50-1 of local station) of optical demultiplexer 34 taps to 50-n by the light signal (will add to 50-n) of optical multiplexer 34 addings from the 50-1 of local station.Therefore, have to regulate simultaneously and will be sent to the 50-1 of local station to the dispersion measure between a plurality of light signals of a plurality of wavelength of 50-n skew and the advantage that is offset to the dispersion measure between a plurality of light signals of 50-n from the 50-1 of local station.

In addition, owing to can be provided with by the predetermined ratio R that second dispersion compensator 35 uses the overcompensation amount to carry out dispersion compensation processing (in the second dispersion compensation step) to being used for, make it along with the transmission range of (N-1) increases gradually to relay 30-1 to 30-from the transmission terminal installation 10 on the optical transmission line 40, so can realize and the similar advantage of described first embodiment above.

Note, though need for distribute to each optical wavelength that the 50-1 of local station is used to send and receive to 50-n provide above-mentioned Variable Dispersion Compensator 38-1 to 38-n and 39-1 to 39-n, but because they are used for the relatively little dispersion measure of residual dispersion slope is compensated, so they can have the dispersion measure of little variable range, therefore can use more cheap and undersized device to realize.

The 4th of [E] first embodiment improves

Figure 17 is the block diagram according to the 4th improved wavelength division multiplexing light relay transmission system 1E of first embodiment of the invention.With reference to Figure 17, shown wavelength division multiplexing light relay transmission system 1E is different with the wavelength division multiplexing light relay transmission system 1A of described first embodiment above, its difference is that the amplifier 13 that will send terminal installation 10 forms dispersion compensator/amplifier 13D, and according to the transmission conditions such as type, transmission range and the bit rate of optical fiber chromatic dispersion compensation quantity among dispersion compensator/amplifier 13D is set.

Except above-mentioned dispersion compensator/amplifier 13D, the structure of wavelength division multiplexing light relay transmission system 1E is basic with above described first embodiment is identical.

Particularly, the chromatic dispersion compensation quantity DCT among dispersion compensator/amplifier 13D is set to-D as shown in figure 18 _T, therefore, first dispersion compensator 32 of relay 30-1 in the 30-(N-1) use with by general+D _TThe compensation rate that equates with the compensation rate of using among above-mentioned first embodiment (with reference to expression formula [3a]) the resulting value of addition is carried out dispersion compensation and is handled.Similarly, second dispersion compensator 35 uses and passes through general-D _TThe overcompensation amount that equates with the compensation rate of using among above-mentioned first embodiment (with reference to expression formula [3b]) the resulting value of addition is carried out dispersion compensation and is handled.

Therefore, for middle wave band λ ₂₂Light signal, dispersion compensating device/image intensifer 21 carries out behind the dispersion compensation can being reduced to zero at the residual dispersion of the position of the wave band classification apparatus (band dividingapparatus) of the position of optical demodulator 22.In addition, send terminal installation 10 and receiver terminal device 20 according to the compensation of being undertaken by compensation rate DCR in dispersion compensator/amplifier 21 of being responsible for the receiver terminal device 20 among above-mentioned first embodiment such as the transmission conditions of fiber type, transmission range and bit rate.

Therefore, in the 4th of first embodiment of the invention is improved, also can realize similar advantage with above-mentioned first embodiment.In addition, can be responsible for the compensation undertaken by compensation rate DCR in the dispersion compensator/amplifier 21 of the receiver terminal device 20 among above-mentioned first embodiment owing to send terminal installation 10 and receiver terminal device 20, so wavelength division multiplexing light relay transmission system 1E has the advantage that the optimum dispersion compensation function can be set according to transmission conditions.

In be improved to the 3rd improved wavelength division multiplexing light relay transmission system 1A, 1A ' and the 1B transmission terminal installation 10 in the 1D according to first of above-mentioned first embodiment and first embodiment, similar with the situation of Figure 17, also dispersion compensator/amplifier the 13D with chromatic dispersion compensating function can be applied to send the amplifier 13 of terminal installation 10.Yet in this example, chromatic dispersion compensation quantity is set to zero.

In addition, can improve to 1D first to the 3rd improved wavelength division multiplexing light relay transmission system 1B very naturally, the chromatic dispersion compensation quantity among dispersion compensator/amplifier 13D is provided with according to transmission conditions such as fiber type, transmission range and bit rate according to above-mentioned first embodiment.

[F] second embodiment

Figure 19 is the block diagram according to the wavelength division multiplexing light relay transmission system 2 of second embodiment of the invention.With reference to Figure 19, shown wavelength division multiplexing light relay transmission system 2 is different with wavelength division multiplexing light relay transmission system 1A according to above-mentioned first embodiment, and its difference is, it comprise with above with reference to the described similar dispersion compensator of Figure 17/amplifier 13D.Wavelength division multiplexing light relay transmission system 2 is also different with wavelength division multiplexing light relay transmission system 1A aspect the pattern of carrying out dispersion compensation by the first dispersion compensator 32F of relay 30-1 in the 30-(N-1) and the second dispersion compensator 35F.Note, except above-mentioned dispersion compensator/amplifier 13D and relay 30-1 to 30-(N-1), wavelength division multiplexing light relay transmission system 2 has the substantially the same structure of wavelength division multiplexing light relay transmission system 1A with above-mentioned first embodiment.

Particularly, the chromatic dispersion compensation quantity DCT among dispersion compensator/amplifier 13D is set to-D _TAnd the chromatic dispersion that comprises in the wavelength-division-multiplexed optical signal of the first dispersion compensator 32F of each relay 30-1 in the 30-(N-1) to the propagation in the 40-(N-1) of 40-1 between the relay area that sends terminal installation 10 sides compensates, make it be in (for example, dispersion measure is reduced to zero) in the tolerance that sets in advance.

In addition, each relay 30-1 uses an overcompensation amount that the wavelength-division-multiplexed optical signal that has carried out Optical Add Drop Multiplexer processing (with reference to Fig. 2) by optical demultiplexer 33 and optical multiplexer 34 is carried out dispersion compensation to the second dispersion compensator 35F among the 30-(N-1) and handles, and the summation of the chromatic dispersion that occurs between the summation that makes the compensation rate among compensation rate and the second dispersion compensator 35F among the dispersion compensator 32F that wins and relay area becomes predetermined ratio.This predetermined ratio that is used to use this overcompensation amount to carry out dispersion compensation is provided with, makes it along with reducing gradually from the transmission range that sends terminal installation 10 (N-1) position to relay 30-1 to 30-.

More specifically, when using D ₁Middle wavelength X between the expression relay area among the 40-1 ₂₂Light signal in occur dispersion measure the time, for example can use the optimum dispersion compensation amount DCLa#1 among the first dispersion compensator 32F of the above-mentioned relay 30-1 of expression formula given below [6a] expression.Therefore, first dispersion compensator 32 of relay 30-1 can be with the intermediate frequency λ among the 40-1 between relay area ₂₂Light signal in the chromatic dispersion that occurs to suppress be zero (with reference to the some C of Figure 20 ₁).

DCLa#1＝-D ₁+D _T…[6a]

Simultaneously, shown in expression formula [6b], for example the overcompensation amount DCLb#1 among the second dispersion compensator 35F of relay 30-1 can be defined as by will be in the middle wavelength X among the above-mentioned relay 40-1 ₂₂The middle dispersion measure D that occurs ₁Multiply by value that fixing non-penalty coefficient γ (penalty coefficient is 1-γ) obtains and the overcompensation amount-D among dispersion compensator/amplifier 13D _TThe value (with reference to Figure 20) that addition obtains.

DCLb#1＝-D _T+(γ×D ₁)＝+γD ₁-D _T…[6b]

In addition, when using D ₂Expression by due to the 40-2 between relay area in middle wavelength X ₂₂Light signal in occur dispersion measure the time, for example can use the optimum dispersion compensation amount DCLa#2. among the first dispersion compensator 32F of the above-mentioned relay 30-2 of expression formula given below [7a] expression

Particularly, because light signal is being transferred to the moment of 40-2 between relay area, middle wavelength X from relay 30-1 ₂₂The dispersion measure of light signal be by the represented value of expression formula [6b], so will be by with dispersion measure D by the dispersion measure of the first dispersion compensator 32F compensation of relay 30-2 ₂With the value (with reference to Fig. 3) that is obtained by the represented value addition of expression formula [6b].Notice that actual compensation rate is to convert the value that negative value obtains to by the value with this dispersion measure.

DCLa#2＝-(+γD ₁-DT+D ₂)＝-γD ₁-D ₂+D _T…[7a]

In addition, shown in expression formula [7b], for example the overcompensation amount DCLb#1 among the second dispersion compensator 35F of relay 30-2 can be defined as the accumulated chromatic dispersion amount D that occurs among 40-1 and the 40-2 by will be between above-mentioned two relay area ₁+ D ₂Value that multiply by fixing non-penalty coefficient γ and obtain and the overcompensation amount-D among dispersion compensator/amplifier 13D _TThe value (with reference to Figure 20) that addition obtains.

DCLb#2＝-D _T+γ(D ₁+D ₂)…[7b]

Also can with above-mentioned relay 30-1 and 30-2 in relay 30-3 is calculated to the first dispersion compensator 32F and the second dispersion compensator 35F among the 30-(N-1) similarly.

Expression formula [8a] has been represented to be used for by relay 30-i[i; 2 to N-1] in the optimum dispersion compensation rate DCLa#i that compensates of the first dispersion compensator 32F.By compensation rate DCLa#i, each relay 30-2 can be with the middle wavelength X of 40-2 between the relay area of previous stage in the 40-(N-1) to the first dispersion compensator 32F of 30-(N-1) ₂₂Light signal in the chromatic dispersion that occurs be reduced to zero (with reference to the some C of Figure 20 ₂To C _N-1).

Simultaneously, another expression formula [8b] has represented to be used for relay 30-i[i; The overcompensation amount DCLb#i (with reference to Figure 20) of the compensation among the second dispersion compensator 35F 2 to N-1].

$\mathrm{DCLa}\#i=-\mathrm{\&gamma;}\underset{j=1}{\overset{i-1}{\mathrm{\&Sigma;}}}{D}_j-D_i+D_T\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left[8a\right]$

$\mathrm{DCLb}\#i=+\mathrm{\&gamma;}\underset{j=1}{\overset{1}{\mathrm{\&Sigma;}}}{D}_j-D_T\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left[8b\right]$

Particularly, can use the intermediate frequency λ of the wavelength-division-multiplexed optical signal of propagating by 40-between relay area (i-1) ₂₂The middle chromatic dispersion D that occurs _iAnd the accumulated value of the overcompensation amount of 40-1 in the 40-(i-1) obtains optimum dispersion compensation amount DCLa#i among the first dispersion compensator 32F between relay area.In addition, according to the above expression formula that provides [8b], when the transmission range to transmission terminal installation 10 increased, the overcompensation amount reduced (absolute value of the value of expression formula [8b] reduces).

In addition, provide the ratio R of the summation of the dispersion compensation value in the dispersion compensation value among the second dispersion compensator 35F and the first dispersion compensator 32F and the second dispersion compensator 35F among the above-mentioned relay 30-1 by expression formula [9-1] ₁In addition, use the result of expression formula [8a] and expression formula [8b], provide the ratio R of the summation of the dispersion compensation value in the dispersion compensation value among the second dispersion compensator 35F and the first dispersion compensator 32F and the second dispersion compensator 35F among the relay 30-i by another expression formula [9-i] _iNotice that the situation that expression formula [9-i] also can be applied to i=1 (is R ₁).

${\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="A20041000318800331.png,A20041000318800341.png"\; state="\{\{state\}\}">R</figure-callout>}}_1=\frac{\mathrm{\&gamma;}{D}_1-D_T}{-{\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="A20041000318800331.png,A20041000318800341.png"\; state="\{\{state\}\}">D</figure-callout>}}_1+D_T+\mathrm{\&gamma;}{D}_1-D_T}=\frac{\mathrm{\&gamma;}{D}_1-D_T}{D_1(\mathrm{\&gamma;}-1)}\&CenterDot;\&CenterDot;\&CenterDot;[9-1]$

$R_i=\frac{\mathrm{\&gamma;}\underset{j=1}{\overset{i}{\mathrm{\&Sigma;}}}{D}_j-D_T}{-\mathrm{\&gamma;}\underset{j=1}{\overset{i-1}{\mathrm{\&Sigma;}}}{D}_j-D_i+D_T+\mathrm{\&gamma;}\underset{j=1}{\overset{i}{\mathrm{\&Sigma;}}}{D}_i-D_T}=\frac{\mathrm{\&gamma;}\underset{j=1}{\overset{i}{\mathrm{\&Sigma;}}}{D}_j-D_T}{D_i(\mathrm{\&gamma;}-1)}\&CenterDot;\&CenterDot;\&CenterDot;[9-i]$

Here, if the interval 40-1 of suppose relay each in the 40-(N-1) is all formed by the monomode fiber (SMF) of about 100km, then can relay area between 40-1 be set to equal substantially each other dispersion measure D to the transmission line dispersion measure of 40-(N-1).In this case, can with more than the expression formula [9-i] that provides be expressed as following formula [9 '].

$R_i=\frac{\mathrm{\&gamma;}\underset{j=1}{\overset{i}{\mathrm{\&Sigma;}}}{D}_j-D_T}{D_i(\mathrm{\&gamma;}-1)}=-\frac{\mathrm{\&gamma;}\&times;i}{1-\mathrm{\&gamma;}}+\frac{D_T}{D(1-\mathrm{\&gamma;})}\&CenterDot;\&CenterDot;\&CenterDot;\left[9^{,}\right]$

Here, the last item of expression formula [9 '] has negative value, when the position of relaying device 30-i when the distance that sends terminal installation 10 increases, this value reduces, then one have fixing on the occasion of.In other words, can be to the ratio R of the chromatic dispersion compensation quantity summation among the overcompensation amount among the second dispersion compensator 35F and the first dispersion compensator 32F and the second dispersion compensator 35F _iBe provided with, make when the position of relaying device 30-i when the distance that sends terminal installation 10 increases, that is, and when relaying device 30-i when sending the transmission range increase of terminal installation 10, gradually change (reducing gradually).

In wavelength division multiplexing light relay transmission system 2 with above-mentioned structure according to second embodiment of the invention, also to first embodiment in similar, the compensation of the best is carried out in the chromatic dispersion that comprises in the wavelength-division-multiplexed optical signal that the first dispersion compensator 32F propagates to 40-(N-1) 40-1 between by the relay area that sends terminal installation 10 sides, make it be in the tolerance that sets in advance (the first dispersion compensation step), and be provided with by the ratio R (with reference to expression formula [9 ']) that the second dispersion compensator 35F uses the overcompensation amount to carry out dispersion compensation processing (in the second dispersion compensation step) being used for, make it along with relay 30-1 reduces away from the transmission terminal installation 10 on the optical transmission line 40 gradually to the position of 30-(N-1).

Therefore, according to second embodiment of the invention, the compensation of the best is carried out in the chromatic dispersion that comprises in the wavelength-division-multiplexed optical signal that the first dispersion compensator 32F propagates to 40-(N-1) 40-1 between by the relay area that sends terminal installation 10 sides, make it be in after the tolerance interior (the first dispersion compensation step) that sets in advance, can carry out Optical Add Drop Multiplexer by optical demultiplexer 33 and optical multiplexer 34 and handle (referring to Fig. 2) (Optical Add Drop Multiplexer step).Therefore, can be to carrying out best compensation to the chromatic dispersion of the light signal of 50-n reception, to improve the characteristic of receiving optical signals by the 50-1 of local station.In addition, the ratio R of the chromatic dispersion compensation quantity summation of the overcompensation amount of the second dispersion compensation step and the first and second dispersion compensation steps is provided with, makes it along with the transmission range from the transmission terminal installation on the optical transmission line to relay reduces gradually.Therefore, can carry out best compensation to the waveform deterioration of the light signal of each wavelength of receiving by receiver terminal device 20.

In addition, in according to first to the 3rd improved wavelength division multiplexing light relay transmission system 1B of above-mentioned first embodiment transmission terminal installation 10 in the 1D, similar to the situation of Figure 19, very naturally, can be provided with at the predetermined ratio R that the second dispersion compensation step uses the overcompensation amount to carry out the dispersion compensation processing being used for, make it begin to reduce gradually along with transmission range from the overcompensation amount-DT that sends terminal installation 10.

[G] other

In the above-described embodiment, relay 30-1 to above detailed description is provided with to 30-(N-1), to form amplifier 31 and 36 and dispersion compensator 32 and 35 as shown in Figure 2 with being separated from each other, according to the present invention, relay 30-1 is not limited thereto to the structure of 30-(N-1), for example amplifier 31 and first dispersion compensator 32 or amplifier 36 and second dispersion compensator 35 can also be formed single circuit.

The invention is not restricted to above-mentioned specific embodiment,, can carry out multiple changes and improvements without departing from the scope of the invention.

Claims (12)

1. wavelength division multiplexed light relay transmission method, be used for carrying out the relay transmission of wavelength multiplexing light signal along optical transmission line, this optical transmission line will send terminal installation and receiver terminal device interconnection, and have between the relay area of separating by a plurality of relays, this wavelength division multiplexed light relay transmission method is characterised in that:

This wavelength division multiplexed light relay transmission method comprises that these steps comprise by being arranged on a plurality of steps that these each described relays of separating the end points place between relay area are carried out:

The first dispersion compensation step (S1), the chromatic dispersion that comprises in the wavelength multiplexing light signal to propagation between the separation relay area that sends the terminal installation side compensates, and makes it be in the tolerance that sets in advance;

Optical Add Drop Multiplexer step (S2) is carried out Optical Add Drop Multiplexer to each wavelength components of having carried out the wavelength multiplexing light signal that dispersion compensation handles in the first dispersion compensation step and is handled; And

The second dispersion compensation step (S3), using an overcompensation amount that the wavelength multiplexing light signal that has carried out the Optical Add Drop Multiplexer processing in the Optical Add Drop Multiplexer step is carried out dispersion compensation handles, the chromatic dispersion that occurs in making between summation and the separation relay area that sends the terminal installation side of the compensation rate of the second dispersion compensation step and the compensation rate of the first dispersion compensation step becomes predetermined ratio, and resulting signal is sent between the separation relay area of receiver terminal device side; And

Ratio to the chromatic dispersion compensation quantity summation of the overcompensation amount of the second dispersion compensation step and the first and second dispersion compensation steps is provided with, and makes it along with the position at the above relay place of described optical transmission line gradually changes apart from the transmission range of described transmission terminal installation.

2. wavelength division multiplexed light relay transmission method according to claim 1, it is characterized in that: be provided with in the described predetermined ratio that the second dispersion compensation step is carried out the dispersion compensation processing with described overcompensation amount being used for, make it increase gradually along with the transmission range of the described transmission terminal installation of position distance of described the above relay of optical transmission line.

3. wavelength division multiplexed light relay transmission method according to claim 1, it is characterized in that: be provided with being used for carrying out the described predetermined ratio that the dispersion compensation of described overcompensation amount handles, make it along with the position of described the above relay of optical transmission line reduces gradually apart from the transmission range of described transmission terminal installation in the second dispersion compensation step.

4. according to any one the described wavelength division multiplexed light relay transmission method in the claim 1 to 3, it is characterized in that: this wavelength division multiplexed light relay transmission method also comprises the residual chromatic dispersion compensation step of being carried out by each described relay, when before handling and afterwards residual dispersion occurring in the light signal at each wavelength, this residual dispersion is compensated in the Optical Add Drop Multiplexer of Optical Add Drop Multiplexer step.

5. according to any one the described wavelength division multiplexed light relay transmission method in the claim 1 to 3, it is characterized in that: this wavelength division multiplexed light relay transmission method also comprises transmitter side dispersion compensation step, satisfies the dispersion compensation of the transmission conditions of the wavelength multiplexing light signal that will send and handle in described transmission terminal installation.

6. wavelength division multiplexed light relay transmission method according to claim 5 is characterized in that: described transmission conditions relate at least one in type, transmission range and the bit rate of optical fiber.

7. relay that is used for the wavelength division multiplexing light relay transmission system, in this wavelength division multiplexing light relay transmission system, sending terminal installation and receiver terminal device is interconnected by optical transmission line, separated by a plurality of relays between the relay area of this optical transmission line, to carry out the relay transmission of wavelength multiplexing light signal, it is characterized in that described relay comprises:

The first dispersion compensation portion (32) is used for the chromatic dispersion that comprises in the wavelength multiplexing light signal of having propagated between the separation relay area that sends the terminal installation side is compensated, and makes it be in the tolerance that sets in advance;

Optical Add Drop Multiplexer portion (33) is used for that each wavelength components of having carried out the wavelength multiplexing light signal of dispersion compensation in the described first dispersion compensation portion is carried out Optical Add Drop Multiplexer and handles; And

The second dispersion compensation portion (35), be used to use an overcompensation amount to carry out dispersion compensation and handle to having carried out wavelength multiplexing light signal that Optical Add Drop Multiplexer handles by described Optical Add Drop Multiplexer portion, make between summation and the separation relay area that sends the terminal installation side of the compensation rate of the described second dispersion compensation portion and the compensation rate of the described first dispersion compensation portion in the chromatic dispersion of appearance become predetermined ratio.

8. relay according to claim 7 is characterized in that: the described second dispersion compensation portion increases the described predetermined ratio that is used for carrying out with described overcompensation amount the dispersion compensation processing gradually along with the transmission range of the described transmission terminal installation of the above relay of described optical transmission line residing position distance.

9. relay according to claim 7 is characterized in that: the described second dispersion compensation portion reduces to be used for carrying out the described predetermined ratio that dispersion compensation is handled with described overcompensation amount along with the transmission range of the described transmission terminal installation of the above relay of described optical transmission line residing position distance gradually.

10. according to any one the described relay in the claim 7 to 9, it is characterized in that: at least one in the described first dispersion compensation portion and the second dispersion compensation portion formed by the variable dispersion compensation arrangement, and this variable dispersion compensation arrangement can change the set point of chromatic dispersion compensation quantity.

11. according to any one the described relay in the claim 7 to 10, it is characterized in that: described relay also comprises the dispersion slope compensation device, is used for compensating with the wavelength multiplexing light signal that will be input to described Optical Add Drop Multiplexer portion or from the relevant chromatic dispersion gradient of the wavelength multiplexing light signal of the described Optical Add Drop Multiplexer portion output of described a plurality of relays different.

12. according to any one the described relay in the claim 7 to 11, it is characterized in that: described relay also comprises dispersion compensator, be used for the residual dispersion amount relevant with the chromatic dispersion compensation quantity in the described first and second dispersion compensation portions being compensated for each light signal by the individual channel of described Optical Add Drop Multiplexer portion insertion/tap.

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